Edge-rolling stand for steel slabs or the like

ABSTRACT

An edge-rolling stand for reducing the width of hot steel slabs, especially those formed in a continuous casting operation, where the edge-rolling stand is used in conjunction with horizontal roll stands. Important feature is that the edging rolls can be changed quickly with all necessary steps performed from operator&#39;&#39;s usual station. Embodies a combined upper guide for the slab and carrier for the rolls readily picked up and carried by overhead crane. Each roll has alternative passes, either of which can be used for rolling, and changeovers to the other pass can be effected quickly.

United States Patent [111 3,583,196

[72] Invento F d! K-Q ley 3,367,162 2/1968 Kazebee et al 72/237 Borough of Churchill, Pa. 2,011,686 8/1935 Mikaelson et al 72/239 gm" 3: 1968 Primary Examiner-Milton s. Mehr I v [45] patented June 8,1971 Attorney-Walter P. Wood [73] Assignee United States Steel Corporation [54] EDGE-ROLLING STAND FOR STEEL SLABS 0R :2 Drawing Figs ABSTRACT: An edge-rolling stand for reducing the width of hot steel slabs, especially those formed in a continuous casting U.S. CL operation where the edgeqouing stand is used in conjunction [BL C| 31/08 with horizontal roll stands. Important feature is that the edging [50] Field olSearch 72/237,

rolls can be changed quickly with all necessary steps per- 234 formed from operator's usual station. Embodies a combined ,uppcr guide for the slab and carrier for the rolls readily picked [56] Rderenm Cited up and carried by overhead crane. Each roll has alternative UNITED STATES PATENTS passes, either of which can be used for rolling, and chan- 2,575,231 I 1/1951 OMalley 72/239 geovers to the other pass can be effected quickly.

PATENTEDJUN em 3.1583196 SHEEIIUF? I TH 1L INVENTOR FHA/WIS K. OUALEY Allama PATENTEU Juri m 3583196 SHEET 2 BF 7 INVENTOR FRANCIS K. OUALEY Altomey SHEET 5 OF 7 INVE/VT'OR FRANCIS K. OUALEY y M/WM AI lorney PATENTEDJUN 819w 34 583,196

SHEET TUF 7 INVENTOR FRANCIS K. OUALE) mjl /hv-L Alla/nay EDGE-ROLMNG STAND FOR STEEL SLABS OR THE MKE This invention relates to an improved edge-rolling stand for reducing the width of steel slabs or the like.

Although the invention is not thus limited, my roll stand is particularly useful for reducing steel slabs formed in a continuous casting operation. When thus used, two successive vertical or edge-rolling stands of my invention are placed between two horizontal roll stands. The horizontal and vertical stunds cooperate to reduce the total cross section of a slab quite drastically in one closely coupled operation with the slab under tension and while it remains at a sufficiently high temperature for hot-rolling. Reference can be made to lenks et al. U.S. Pat. No. 3,358,358 for showing of the method and to Kazebee et al. U.S. Pat. No. 3,367,162 for a showing of an earlier form of edge-rolling stands used in carrying out the method. ln rolling mills of this type, it is frequently necessary to change rolls. One difficulty with previous edge-rolling stands has been that changing rolls takes too long, and necessitates stopping the whole operation with a resulting loss of production. Preferably I use the edge-rolling stands of my present invention in conjunction with horizontal stands constructed as shown and claimed in my copending application Ser. No. 714,564, filed Mar. 20, I968 to facilitate changing the horizontal rolls.

An object of my invention is to provide an improved edgerolling stand, the rolls of which can be taken out and replaced during the brief intervals after a slab has been rolled before the next arrives without interrupting the normal tempo of the operation.

A further object is to provide an improved edge-rolling stand, the rolls of which can be changed by remote control from the operators usual station.

A further object is to provide an improved edge-rolling stand in which the rolls of two adjacent stands can be handled together and change expeditiously in a single operation.

A further object is to provide an improved edge-rolling stand which affords two alternative roll passes, one above the other, and means for quickly positioning the rolls to enable either pass to be used.

A further object is to provide an improved edge-rolling stand which includes a combined upper guide for slabs passing through the stand and carrier for the rolls as they are taken out or replaced.

In the drawings:

PEG. 1 is a vertical longitudinal sectional view of a sevenstand rolling mill embodying edge-rolling stands constructed in accordance with my invention with the combined guide and carrier removed;

H0. 2 is a vertical cross section on a larger scale one line ll- -ll of HO. 1;

FlG. 3 is a vertical longitudinal section of the edge-rolling stand on a still larger scale with parts broken away;

FlG. 4 is a cross section similar to FIG. 2, but on a larger scale and with additional parts broken away;

HO. 5 is a horizontal section on line V-V of FIG.

HO. 6 is a longitudinal section on line Vl-Vl of FIG. 6;

FIG. 7 is a longitudinal section on line Vll-Vll of H6. 4 showing the combined guide and carrier;

MG. 8 is a horizontal section on line Vlll-Vlll of FIG. 7; and

FIG. 9 is an end elevational view of the combined guide and carrier.

MILL LAYOUT FIG. 1 shows a seven-stand rolling mill which includes three horizontal roll stands 10, 12 and 13 and four vertical or edgerolling stands 14, 15, 16 and 17. The horizontal roll stands can be of any standard or desired construction, but as already pointed out, l prefer the construction shown in my aforementioned application. The edgerolling stands are constructed in accordance with my present invention. The two edge-rolling stands 14 and 15 are located between the horizontal stands 10 and 12, and the two edge-rolling stands 16 and 17 between the horizontal stands 12 and 13. A slab S, which may be formed in a continuous casting machine and is at a suitable temperature for hot-rolling, travels through the mill from left to right. The exit sides of the horizontal roll stands 10 and 12 carry watercoooled guides 18 which direct the slab into the edge-rolling stands 14 and 16 respectively. The entry sides of the horizontal roll stands 12 and 13 carry water-cooled guides 19, which direct the slab into these stands. The mill maintains the slab under tension, while the horizontal and edge-rolling stands reduce its thickness and width respectively, as explained more fully in the aforementioned .lenks et. al. patent. A traveling crane 20 of any standard or desired construction is supported above the roll stands for handling the rolls, etc.

When the mill is used with slabs formed in a continuous casting operation, I prefer to apply pressure to the rolls of all the horizontal and edge-rolling stands by hydraulic mechanisms which are equipped with emergency dump valves. This arrangement enables the roll pressure to be released immediately without damaging the rolls in the event a slab is oversized or too cool for rolling. I set the mechanism so that the dump valves open automatically whenever the roll pressure exceeds allowable limits. Reference can be made to my earlier U.S. Pat. No. 3,280,6l0 for a showing of a horizontal stand thus equipped. Although I do not show the hydraulic system in detail for the edge-rolling stands, preferably it includes an emergency dump valve as my earlier patent shows.

EDGE-ROLLING STANDS-GENERAL As FIG. 2 shows, each two adjacent edge-rolling stands 14 and 15 (or 16 and 17) have a common base 21 and a common opposed pair of roll housings 22 and 22a slidably supported on the base for movement toward and away from the longitudinal centerline of the base. The base carries a pair of ram crossheads 23 (only one shown) outside the respective housings. The crosshead shown carries a hydraulic ram cylinder 24 and a pair of hydraulic pullback cylinders 25. The ram cylinder contains a reciprocable ram 26 which engages the housing 22 for forcing it toward the longitudinal centerline and thus applying rolling pressure to the slab. The pullback cylinders contain reciprocable pistons and piston rods 27 which are connected to housing 22 for pulling it back when pressure in the ram cylinder is relieved. Accordion-pleated boots 28 cover the piston rods to exclude foreign material. The other ram crosshead is similarly equipped for moving the housing 22a. The base 21 carries a fixed lower guide 29 for the slab intermediate the two housings. The guide preferably is water-cooled, except for narrow sizes where there is insufficient room. The mechanisms for supporting and moving the housings follow known principles, for example as shown in the aforementioned Kazebee et al. patent; hence l have not described them in more detail.

The mechanisms carried by the two roll housings 22 and 22a are similar. The mechanisms of the two roll stands 14 and 15 (or16 and 17) likewise are similar, except that the rolls are spaced more closely in each succeeding stand from left to right as viewed in FlG. l to define progressively narrower passes, and same parts are of opposite hand, as hereinafter noted. Hence I show and describe in detail only the mechanism carried by the housing 22 for the first edge-rolling stand 14.

ROLL CHOCKS AND ROLLS As FIGS. 2, 3 and 4 show, the floor of housing 22 carries an upstanding hydraulic cylinder 32 which has a vertically reciprocable plunger 33. l mount a vertically slidable roll chock 34 in the housing overlying the plunger 33. The chock has upper and lower bearings 35 which are held in place by caps 36 and in which I journal a roll 37 for rotation on a vertical axis. The side of the chock facing the opposed chock is open between the upper and lower caps 36, as indicated at 38 (FIG. 4) and the roll projects through this opening. Roll 37 has upper and lower passes 37:: and 37b. When plunger 33 is retracted, chock 34 and roll 37 are in a down position in which the upper class 37a is aligned with guide 18 to receive a slab S. When the plunger is extended, it pushes the chock and roll to an up position in which the lower pass 371) is aligned with the guide to receive the slab as shown for the roll stand I at the right of FIG. 3.

The housing has a shelf 39 spaced above its floor on which I mount a slidable step block 40 and an operating cylinder 4] therefor behind the chock. When the roll and chock are operating in their up position, I project the step block under the chock to furnish support; otherwise the step block is retracted. The back of chock 34 has a first pair of sockets 42 in its upper edge and a second pair of sockets 42a spaced therebelow (FIG. 4). The housing 22 carries two lockpins 43,

which extend through its inner longitudinal wall, and operating cylinders 44 for the pins (FIGS. 2 and 6). I operate the latter cylinders to project the lockpins into sockets 42a when the chock is in its down position, or into sockets 42a when the chock is in its up position, to act as a holddown.

Any of my edge-rolling stands can be used with one roll in the up position and the other down, or both can be up, or both down. FIG. 3 shows the roll of stand I4 in its down position and the roll of stand in its up position. This arrangement enables me to shift any roll quickly to use the other pass whenever the pass in use shows excessive wear.

As FIGS. 4 and 5 show, the back of chock 34 has inwardly directed opposed guideways 47 along its vertical edges. The inner longitudinal wall of housing 22 behind the chock carries a pair of studs 48 on which I pivot respective levers 49 (FIGS. 4 and 6). I mount a pair of horizontally slidable guide and locking plates 50 in slots M in the adjacent transverse walls of the housing and connect the plates to levers 49 through links 52 (FIG. 6). I also connect the levers to an actuating rod 53, which extends upwardly to an operating cylinder 54 therefor. When rod 53 is in its retracted or up position, plates 50 project into guideways 47 and hold the chock 34 in the housing, but serve also to guide it when it moves vertically. When rod 53 is projected to its down position, the plates are withdrawn from the guideways to permit removal of the roll and chock from the housing, as hereinafter explained.

ROLL DRIVE As FIGS. 3 and 4 show, roll 37 has an extension 57 of noncircular cross section above the upper bearing 35. A vertically movable coupling sleeve 58 slidably receives this extension. The inner longitudinal wall of housing 22 carries a guide bracket 59 for the sleeve. The upper portion of sleeve 58 has internal splines, and slidably receives a spline shaft 60. When roll 37 is shifted between its up and down positions, sleeve 58 moves vertically with the roll, and there is sufficient clearance between the ends of extensions 57 and shaft 60 not to interfere. The upper end of shaft 60 carries a flexible coupling which I connect to a suitable drive 62 indicated in FIGS. 1 and 2 but not shown in detail. I mount the drive on a support 63 fixed to the top of housing 22 (FIGS. 2, 3 and 6). The aforementioned cylinder 54 also is mounted on the drive support 63 (FIG. 6). The drive support 63a for the edge-rolling stand 15 at the other end of housing 22 is of opposite hand. An accordion-pleated boot 64 covers shaft 60 to exclude foreign material.

I pivot a bellcrank 65 and an operating cylinder 66 therefore in the drive support 63 (FIG. 3). The cylinder has a piston rod 67 pivoted to a central arm of the bellcrank. The latter has two arms which straddle the coupling sleeve 58 and have rollers 68 joumaled at their ends. The upper end of sleeve 58 has an external flange 69 overlying rollers 68 and adapted to be engaged thereby. To permit removal of the roll and chock from the housing, I operate cylinder 66 to retract piston rod 67 and pivot the bellcrank 65 upwardly. This lifts the coupling sleeve 58 to a position where its lower end clears the extension 57 of the roll.

COMBINED UPPER GUIDE AND ROLL CARRIER As FIG. 7 shows, the housings of the two horizontal roll stands I0 and 12 carry cheek plates 72 spaced below their upper ends facing the housing 22 of the edge-rolling stands 14 and 15. These cheek plates have sockets 73 open at the top and toward each other. The faces of the sockets taper downwardly in three planes. The combined upper guide and roll carrier includes an elongated body 74 preferably water cooled where space permits. The ends of body 74 have integral downwardly tapered lugs 75 which fit within the sockets 73 to support the body. The cheek plates have upstanding cars 76 to which I pivot toggle linkages 77. The housings of the horizontal roll stands have outwardly extending cars 78 to which I pivot operating cylinders 79 for the toggle linkages. These cylinders have piston rods 80 which I pivot to the linkages. When the piston rods are extended, the linkages abut the upper faces oflugs 75 and thus lock body 74 in position. When the piston rods are retracted, the toggle linkages break to permit the guide and carrier to be lifted from the roll stand. A pair of upper guide shows 81 for the slab S are fixed to the bottom of body 74.

As FIGS. 7, 8 and 9 show, body 74 carries an upstanding plate 83 and horizontal plates 84 projecting from each side. Each horizontal plate has two arcuate recesses 85 in its outer edge (four altogether), the arcs of which extend more than 180. The plates have upstanding lips 86 around the edges of their recesses. Chock 34 carries a retaining ring 87 which has a downwardly facing lip 88 (FIG. 4). Before removing the chock and roll from the housing, I raise them to their up position and then operate the rams to push housing 22 and 22a to positions nearest the centerline of base 21 (FIG. 2). This places the retaining rings of the four chocks of the edge-rolling stands 14 and 15 (or 16 and 17) immediately above and in vertical alignment with the respective recesses 85, whereby the lips 86 and 88 can engage. I point out that the housings must be pulled back when the chocks and rolls are shifted between their up and down positions, since otherwise the retaining rings 87 do not clear plates 84.

As FIG. 9 shows, the guide and carrier includes a pair of spaced-apart bars 89 fixed to opposite sides of the vertical plate 83 and upstanding therefrom. The bars have vertically elongated openings 90 near their upper ends in which I insert a vertically moving pin 91. A crane hook 92 carried by the overhead crane 20 (FIG. 1) can engage the pin for lifting the guide and carrier. I pivot a pair of levers 93 to the outside of each bar 89 and connect the inner ends of each lever with the ends of pin 91 through respective links 94 (FIG. 7). The vertical plate 83 carries a pair of guides 95 at each side (four altogether) located over the edges of the respective recesses 85. I mount respective locking bars 96 in each guide 95 for vertical movement. I connect the upper ends of the locking bars with the levers 93 through toggle links 97. When the crane lifts the guide and carrier to pick up the four chocks and rolls of two edge-rolling stands, it moves pin 91 upwardly in openings 90. The pin acts through links 94, levers 93 and toggle links 97 to force the locking bars 96 downwardly into abutment with the retaining rings 87 of the chocks, thus locking the rolls in the recesses. When the hook releases the carrier, the locking bars return automatically to their up positions.

OPERATION In reducing a slab S, the edge-rolling stands of my invention operate in a manner similar to that described in the aforementioned Jenks et al. and Kazebee et al. patents. Hence I have not repeated this description. When the stand is set up for rolling the roll chocks 34 are locked in the housings by engagement of Iockpins 43 with sockets 42 or 42a, and engagement of plates 50 with guideways 47. If the lower pass 37b is used, the step block 40 is projected under the chock. The guide and carrier is locked in place by engagement of the toggle linkages 77 with lugs 75.

To remove the four rolls of two adjacent stands, I operate cylinders 44, 54 and 79 to withdraw pins 43 and plates 50 and break the toggle linkage 77. 1 also operate cylinder 66 to raise the coupling sleeve 58. I move the housings 22 and 22a to positions where the retaining rings 87 of the four chocks overlie the recesses 85 of the carrier plates 84, as already described. 1 engage the crane hook 92 with pin 91 and thus lift the guide and carrier and the four chocks and rolls freely from the roll stand. The interengagement of lips 86 on plates 84 and lips 88 on the retaining rings through more than 180, plus the action of the locking bars 96, assures that the carrier does not drop the rolls as the crane transports them. 1 reverse these steps when 1 install the rolls. Since the surfaces of the lugs 75 and sockets 73 taper in three planes, it is not necessary to align the lugs perfectly with the sockets before lowering the guide and carrier into position. The tapered surfaces assure that the parts automatically move into proper alignment.

All the cylinders of course have suitable connections for admitting and discharging hydraulic fluid. Such connections are not shown, since they follow well-known principles. The controls for the various cylinders are located at the operator's usual station. The entire roll-changing operation is handled from this station and the crane cab and requires only a few minutes. Normally I can accomplish this operation in the time it takes for an empty ladle to be replaced in a continuous casting plant, about to minutes.

While I have shown and described only a single embodiment of my invention, it is apparent that modifications may arise. Therefore, 1 do not wish to be limited to the disclosure set forth but only by the scope of the appended claims.

1 claim:

1. In an edge-rolling stand which includes:

a base having a longitudinal centerline;

a pair of housings supported on said base on opposite sides of the centerline;

means on said base connected with said housings for moving them back and forth toward and away from the centerline;

a lower guide for slabs supported on said base between said housings;

roll chocks mounted in the respective housings; and

power-driven rolls joumaled in said chocks for rotation on vertical axes;

the combination therewith of a combined upper guide for slabs and carrier for said chocks and rolls comprising:

an elongated body;

means engaging said body to support it between said housings above said lower guide;

slab-guiding means carried by said body;

means carried by said body engageable with said chocks for carrying the chocks and rolls; and

means carried by said body for lifting the body and chocks and rolls carried thereby.

2. A combination as defined in claim 1 in which each of said housings carries the chocks and rolls of two adjacent stands, and in which said carrying means is engageable with four chocks, two on each side of said body.

3. A combination as defined in claim 1 in which the means engageable with said chocks includes horizontal plates having recesses extending through arcs of at least 180 to receive said chocks, said plates having upstanding lips around said recesses, said chocks having downwardly facing lips engageable with the lips on said plate.

4. A combination as defined in claim 1 in which said guide and carrier includes locking means automatically actuated by said lifting means for locking the chocks therein when said carrier and chocks are lifted from said housings.

5. A combination as defined in claim 1 in which the means engaging the body of said guide and carrier has sockets which open upwardly and inwardly and have faces which taper downwardly in three planes, and said body has correspondingly tapered lugs received in said sockets, whereby said lugs can be inserted in said sockets if not perfectly aligned therewith.

6. A combination as defined in claim 1 in which said rolls have upper and lower passes either of which can be used for rolling and further comprising means in said housings for raising and lowering said chocks and thereby positioning either pass to receive a slab.

7. 1n an edge-rolling stand which includes: a base having a longitudinal centerline; a pair of housings supported on said base on opposite sides of the centerline;

means on said base connected with housings for moving them back and forth toward and away from the centerline;

a lower guide for slabs supported on said base between said housings;

roll chocks mounted in the respective housings; and

power-driven rolls joumaled in said chocks for rotation on vertical axes;

the improvement which comprises;

cooperating guide means on said housings and chocks allowing vertical movement of the chocks;

each of said rolls having upper and lower passes, which rolls can be positioned in the relations (a) the upper passes of both rolls used for rolling, (b) the lower passes of both rolls used for rolling, or (c) the upper pass of either roll and the lower pass of the other roll used for rolling; and

means in said housings for raising and lowering said chocks independently of each other in said guide means and thereby positioning either pass of either roll to receive a slab.

8. A structure as defined in claim 7 in which said guide means includes vertical guideways formed on said chocks, retractable plates mounted on said housings and received in said guideways, and means on said housing connected with said plates for retracting the plates from the guideways, thereby permitting the chocks to be removed from the housmgs.

9. A structure as defined in claim 7 in which the means for raising and lowering said chocks includes respective hydraulic cylinders and plungers mounted in said housings beneath each chock, and respective retractable blocks mounted in said housings for holding the cho'cks in raised position.

10. A structure as defined in claim 7 in which each of said rolls has an extension at its upper end, and including respective coupling sleeves slidably receiving said extensions, respective spline shafts joumaled in said housings and slidably received in said sleeves, said sleeves moving with said chocks and rolls as the rolls are raised and lowered, and means for liftthe chocks and rolls to be removed from the housings.

11. A structure as defined in claim 7 further comprising a combined upper guide for slabs and carrier for said chocks and rolls, means removably supporting said guide and carrier between said housings above said rolls, and means in said housing for moving said chocks into engagement with the carrier to enable the rolls and chocks to be removed from the housings.

12. A combined guide for slabs passing through an edgerolling mill and carrier for the rolls of the mill, said guide and carrier comprising an elongated body, a guide shoe fixed to the underside of said body, a plate extending horizontally from said body and having recesses adapted to receive and support a plurality of roll chocks, and means extending upwardly from said body for lifting the carrier and roll chocks.

13. A guide and carrier as defined in claim 12 further comprising lugs extending from the ends of said body and having surfaces which taper downwardly in three planes, whereby said lugs can be inserted in correspondingly shaped supports without being perfectly aligned therewith.

14. A guide and carrier as defined in claim 12 in which said recesses extend through arcs of at least and said plate has upstanding lips around the edges of the recesses engageable with lips on the roll chocks.

15. A guide and carrier as defined in claim 14 further comprising locking means automatically actuated by the lifting means for locking chocks in place when said lips are engaging.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent 3 ,583 ,196 D d June 8 1971 Inventor(s) Francls K Qualey It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 51, "one" should read on line 58, "6" second occurrence, should read H 4 Column 2, line 6, "coooled" should read cooled line 60, "same" should read some Column 3, line 18, "42a" should read 42 Column 4, line 31, "housing" should read housings line 44, "moving" should read movable Signed and sealed this 7th day of March 1972 (SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents FORM F'O-1OSO (10-69) USCOMM-DC 60376-F'69 e vs oovenmnzm FRINYING OFFICE: can o-:ss-334 

1. In an edge-rolling stand which includes: a base having a longitudinal centerline; a pair of housings supported on said base on opposite sides of the centerline; means on said base connected with said housings for moving them back and forth toward and away from the centerline; a lower guide for slabs supported on said base between said housings; roll chocks mounted in the respective housings; and power-driven rolls journaled in said chocks for rotation on vertical axes; the combination therewith of a combined upper guide for slabs and carrier for said chocks and rolls comprising: an elongated body; means engaging said body to support it between said housings above said lower guide; slab-guiding means carried by said body; means carried by said body engageable with said chocks for carrying the chocks and rolls; and means carried by said body for lifting the body and chocks and rolls carried thereby.
 2. A combination as defined in claim 1 in which each of said housings carries the chocks and rolls of two adjacent stands, and in which said carrying means is engageable with four chocks, two on each side of said body.
 3. A combination as defined in claim 1 in which the means engageable with said chocks includes horizontal plates having recesses extending through arcs of at least 180* to receive said chocks, said plates having upstanding lips around said recesses, said chocks having downwardly facing lips engageable with the lips on said plate.
 4. A combination as defined in claim 1 in which said guide and carrier includes locking means automatically actuated by said lifting means for locking the chocks therein when said carrier and chocks are lifted from said housings.
 5. A combination as defined in claim 1 in which the means engaging the body of said guide and carrier has sockets which open upwardly and inwardly and have faces which taper downwardly in three planes, and said body has correspondingly tapered lugs received in said sockets, whereby said lugs can be inserted in said sockets if not perfectly aligned therewith.
 6. A combination as defined in claim 1 in which said rolls have upper and lower passes either of which can be used for rolling and further comprising means in said housings for raising and lowering said chocks and thereby positioning either pass to receive a slab.
 7. In an edge-rolling stand which includes: a base having a longitudinal centerline; a pair of housings supported on said base on opposite sides of the centerline; means on said base connected with housings for moving them back and forth toward and away from the centerline; a lower guide for slabs supported on said base between said housings; roll chocks mounted in the respective housings; and power-driven rolls journaled in said chocks for rotation on vertical axes; the improvement which comprises; cooperating guide means on said housings and chocks allowing vertical movement of the chocks; each of said rolls having upper and lower passes, which rolls can be positioned in the relations (a) the upper passes of both rolls used for rolling, (b) the lower passes of both rolls used for rolling, or (c) the upper pass of either roll and the lower pass of the other roll used for rolling; and means in said housings for raising and lowering said chocks independently of each other in said guide means and thereby positioning either pass of either roll to receive a slab.
 8. A structure as defined in claim 7 in which said guide means includes vertical guideways formed on said chocks, retractable plates mounted on said housings and received in said guideways, and means on said housing connected with said plates for retracting the plates from the guideways, thereby permitting the chocks to be removed from the housings.
 9. A structure as defined in claim 7 in which the means for raising and lowering said chocks includes respective hydraulic cylinders and plungers mounted in said housings beneath each chock, and respective retractable blocks mounted in said housings for holding the chocks in raised position.
 10. A structure as defined in claim 7 in which each of said rolls has an extension at its upper end, and including respective coupling sleeves slidably receiving said extensions, respective spline shafts journaled in said housings and slidably received in said sleeves, said sleeves moving with said chocks and rolls as the rolls are raised and lowered, and means for lifting said sleeves to positions clearing said extensions to permit the chocks and rolls to be removed from the housings.
 11. A structure as defiNed in claim 7 further comprising a combined upper guide for slabs and carrier for said chocks and rolls, means removably supporting said guide and carrier between said housings above said rolls, and means in said housing for moving said chocks into engagement with the carrier to enable the rolls and chocks to be removed from the housings.
 12. A combined guide for slabs passing through an edge-rolling mill and carrier for the rolls of the mill, said guide and carrier comprising an elongated body, a guide shoe fixed to the underside of said body, a plate extending horizontally from said body and having recesses adapted to receive and support a plurality of roll chocks, and means extending upwardly from said body for lifting the carrier and roll chocks.
 13. A guide and carrier as defined in claim 12 further comprising lugs extending from the ends of said body and having surfaces which taper downwardly in three planes, whereby said lugs can be inserted in correspondingly shaped supports without being perfectly aligned therewith.
 14. A guide and carrier as defined in claim 12 in which said recesses extend through arcs of at least 180* and said plate has upstanding lips around the edges of the recesses engageable with lips on the roll chocks.
 15. A guide and carrier as defined in claim 14 further comprising locking means automatically actuated by the lifting means for locking chocks in place when said lips are engaging. 